There are a number of liquid compositions or diluted mixtures on the market by the name of `Activity drinks`, `Sports drinks`, `Energy drinks` or `Nutrient drinks`. These drinks are reported to solve problems with respect to the loss of carbohydrates, electrolytes, vitamins, minerals, amino acids, and other important nutrients which occurs during heavy exercise. Physical exercise can be distinguished in different categories i.e. those requiring strength, strength and speed or endurance. In practice this can be heavy work, muscle activity under severe conditions (e.g. high temperature, high altitude), leisure sports or athletic performance.
Muscle activity is primarily based on a very fundamental biochemical mechanism, the breakdown of energy-rich phosphate bonds (ATP, adenosine triphosphate). ATP is the direct source of energy for muscle work and is in fact the only form of chemical energy, which can be converted by the muscle into mechanical work.
During high physical activity of the body the ATP level in the muscles diminishes rapidly. Several substrates are available as sources for replenishing the ATP.
When there is low physical activity fats are used for ATP production, at higher activity rates, glycogen in the muscle is the major energy supply. The energy from glycogen (carbohydrate) is released in exercising muscles up to three times as fast as the energy from fat. During the last half century it has been repeatedly demonstrated that exercise of a moderate intensity cannot be maintained when carbohydrate stores within the body are not sufficient or sufficiently available. Carbohydrates are the fuel from which body cells obtain energy for cellular activities and the major portion of carbohydrates utilised by the body are used for ATP production. The energy required for developing athletic activity, and indeed for all muscular work, comes primarily from the oxidation of glycogen stored in the muscles.
Glycogen can be used either relatively slowly via the complete glycolysis and oxidative phosphorylation to form carbon dioxide, water and 38 moles of ATP per mole of glucose. When exercise is very intensive, i.e. so intensive that the respiratory and cardiovascular systems of the body do not have sufficient time to deliver oxygen to the muscles, the energy for this activity will be delivered almost exclusively from anaerobic metabolism, and much less ATP per molecule of glucose is produced. Under these circumstances the athlete accumulates an `oxygen debt` and the athlete's tissues use a mechanism of carbohydrate oxidation that requires no oxygen. The by-product of this oxygen debt is lactic acid. After recovery the system will show a net decrease in total carbohydrate (muscle glycogen) content. This decrease is equivalent to the amount of carbohydrate expended in performing the muscular work.
Fatigue during high intensity exercise may be viewed as the result of a simple mismatching between the rate at which ATP is utilised and the rate at which ATP is produced in working muscles. The attention, given over the last two decades to the study of the limitations of ATP production, leads to the conclusion that the cause of fatigue may be the inability of the metabolic machinery to provide ATP fast enough for the energy needs of the working muscles to sustain force production (D. MacLeod in "Exercise--Benefits, limits and adaptations--1987).
Furthermore, during relatively extended periods of heavy muscle work, the work capacity of an individual is limited by several factors, such as too low blood sugar concentration and loss of liquid by transpiration. In the last decade the use of liquid drinks containing carbohydrates during exercise has become more and more accepted as a stimulus during endurance performance. As a result, these days it is general practice to ingest substantial amounts of carbohydrate in a liquid form during endurance competition events. Supplementation with carbohydrate containing fluids is employed to prolong exercise and improve the performance of high intensity endurance exercise. Benefits to be obtained are: maintenance of fluid balance and an increase in the availability of carbohydrate, the primary substrate for the muscular ATP production.
Carbohydrate feedings during exercise appear to delay fatigue by as much as 30 to 60 minutes. (E. F. Coyle in Advances in Nutrition and Top Sport--Medicine and Sport Science--Volume 32-1991). During the last decade much attention has been focused on the optimum form and type of carbohydrate beverages to prolong physical performance.
Although considerable amounts of carbohydrates can be ingested, not all of the exogenous carbohydrates emptied from the stomach are oxidize during exercise. Gastric emptying rate decreases with increasing carbohydrate concentration and osmolality. Consequently highly concentrated carbohydrate solutions have been observed to increase the frequency of gastrointestinal distress in endurance athletes. According to N. J. Rehrer (J. Appl. Physiol. 72(2): 468-475, 1992) the volume of beverage emptied from the stomach is significantly influenced by the beverage composition. Specially, the concentration of the carbohydrates is of particular importance. The effects of osmolality on gastrointestinal secretions may be more important with respect to rehydration than the effects on gastric emptying. An increase in intestinal secretion instead of absorption is observed with the presence of hypertonic fluid in the intestine.
Three different periods of carbohydrate intake can be defined: pre-exercise intake, intake during exercise and post-exercise intake. Carbohydrate beverages are ingested prior to exercise in an attempt to prevent detrimental changes, which can accompany exercise. The efficiency of ingested glucose in enhancing physical performance is dependent on the time at which the beverage is ingested before exercise. Glucose containing beverages produce an increase in plasma glucose peaking approximately 45 minutes after ingestion. The increase in plasma glucose results in an increase in plasma insulin and a subsequent drop in plasma glucose during the initial period of the activity, resulting in quick exhaustion. In contrast, glucose solutions ingested from 5 minutes to immediately prior to exercise result in maintenance of the blood glucose level throughout moderate- to high-intensity exercise. (Nutrition in Exercise and Sport--CRC Press--1990).
The benefits of carbohydrate consumption during exercise have already been touched upon. A general recommendation is that 20 to 60 g of carbohydrate be consumed every hour during prolonged exercise. The post-exercise intake of carbohydrates to enhance recovery from exercise has not been addressed to the same extent as has the use of carbohydrates to enhance performance during exercise. However, it appears that the rate of muscle glycogen re-synthesis is somewhat more rapid during the first 2 h following exercise compared to the 2 to 4 hour period. Therefore a recovering athlete should eat a high carbohydrate containing meal as soon after exercise as practically possible. (E. F. Coyle in Advances in Nutrition and Top Sport--Medicine and Sport Science--Volume 32-1991).
Different compositions for beverages have been described. International patent application WO 91/12734 describes a hypotonic beverage composition comprising an aqueous solution, either carbonated or non-carbonated, electrolytes, carbohydrates, low-caloric sweetener, and edible acid components.
U.S. Pat. No. 4,312,856 to Korduner et al, describes a beverage product adapted for the replacement of liquid and carbohydrates in the human body during heavy exercise. The product is hypotonic and free of monosaccharides. U.S. Pat. No. 5,397,786 to Simone describes a hypotonic rehydration drink, containing per serving unit at least the following compositions:
a) 1 to 100 g of at least one carbohydrate, PA1 b) 2 to 2500 mg of at least one electrolyte, PA1 c) 0.1 to 750 mg of at least one ammonia neutralizer, PA1 d) at least one energy enhancer, PA1 e) at least one antioxidant, PA1 f) at least one membrane stabilizer, PA1 g) at least one neuromuscular function enhancer selected from the group consisting of choline and a higher saturated fatty alcohol, and PA1 h) water in a quantity at least sufficient for providing a solution wherein components a) to g) are substantially dissolved and which solution is ready for consumption by drinking. This specific combination of components appears to solve a myriad of symptoms relating to dehydration of the human body. PA1 D-ribose, PA1 a blood glucose increasing monosaccharides and, PA1 a blood glucose increasing oligosaccharides and/or hydrogenated glucose syrups PA1 increase of the intracellular level of ATP by supplementation of a pentose, especially D-ribose, PA1 increase of the blood-glucose level by supplementation of glucose and glucose-polymers and/or hydrogenated glucose syrups, and PA1 increasing the water absorption and rehydration by supplementing an essentially isotonic drink. The concentration of the carbohydrates is such that the tonicity (=) measure of the osmotic pressure of a solution relative to the osmotic pressure of the blood fluids) of the blood is the same or is only marginally exceeded. The osmolality of blood usually ranges from about 280 to 310 mOs/kg.
International patent application WO 95/22562 describes an energy formulation comprising a novel dextrin-type starch having a molecular weight of from about 15,000 to about 10,000,000 and wherein the molecules are heavily branched.